DIY coil denitrator output test showin extreme high NO3 and NO2

[ing_monkey]

Hi guys,

several days ago i made coil denitrator from a PET bottle with about 40 ft of airilne tubing classic size used in aquariums. As i didn't find BIO balls in shop, i just filled it with FLUVAL cottonwool which should as well serve as BIO media.

I tested today the output of denitrator using Tetra test for NO3 and NO2. What i was surpriced, NO3 shows extreme high levels already first seconds after adding 3rd substance. Usually it takes longer time to get red colour, so i assume NO3 levels are very high. NO2 also shown extreme high ppm - both over the scale.

Yesterday when testing i just found little bit higher nitrites - around 0.3-0.5 ppm and nitrates were same as in main tank.
What i changed since yesterday was flow of the water going to denitrator from appr 3 drops per second to only 1 drop per 1 or 2 seconds. I did so after reading some forums where guys suggested to decrease the flow during initial phase.

I got afraid if this doesnt mean H2S present in output because i just don't understand such high levels of nitrates in output. They supposed to be same or lower. I understand this device is still just in initial period, so i didnt expect it to reduce nitrates, but to add ?? I tryed to smell the output line, if i can detect some rotten eggs, but i didnt noticed.

I was substantially changing water now almost every day about 10%, because nitrates keep to be high (50-75 ppm). I never had problem with higher nitrites, always showin at trace levels. This is due biological filtering. I also use CO2 injection and recently i let water get more oxygentated by airpump, because fishes tend to keep on the top and gasping for air.

Its 30 gallon planted tank far from being overstocked.

Please help

 

[ing_monkey]

I want to simplify question

OK, after i seen essay of 'old man of the sea' i realized i was writing maybe too much without straightforward question.

My simple question: Is that normal and expected, that denitrator's output has big NO3 ppm ?

What is/could be the reason of high NO3 in denitrator output ?

 

[CaptainAhab]

Are you cycling it in the tank, with tank water out of the tank?

The way I've seen it done is to fill a 5g bucket with old tank water, a heater and airstone. Run the denitrator continuously with that water to cycle it. Once cycled, move it to your tank.

One question, is your denitrator not going to compete with your plants?

Nitrates higher coming out could be an indication that aerobic cycling has begun but anerobic has not thus the nitrates are not being consumed yet.

 

[ing_monkey]

I did in the tank at first, but soon moved it in another small tank with an old tank water.

Why should I use heater ? I currently don't use it even in main tank.

Nitrates higher coming out could be an indication that aerobic cycling has begun but anerobic has not thus the nitrates are not being consumed yet.

Yea, that sounds logical, but thing is, that output has also extreme high NO2. That indicates, that some anaerobic process also started. both nitrites and nitrates are much lower in normal water than in output of the denitrator.

I want to ask there - Do the conditions in cycling tank need to be very similar to normal tank ? Because it might happen after moving it to normal tank, that there would be more O2 content which causes aerobic bacteria not catching with coming oxygen, which could eventually kill anaerobic bacteria and break the process. I am usually not using an airpump in main tank, it seems like plants are producing enough oxygen. Not sure if i should use airpump in cycling tank.

One question, is your denitrator not going to compete with your plants?

I was not thinking about this, currently they are obviously not catching with nitrate production. And i even have duckweed there. But that might be a result of not changing the water for over 3 months...

What i want to achieve is some sort of ecological aquarium, where water changes are not needed at all. Is that even possible ? Could removing all filtering help ?